Homes built today are generally relatively energy efficient. To obtain energy efficiency the homes are substantially air tight and have limited quantities of fresh air added. Scents are added to air tight homes to provide a pleasing fragrance. These scents counter act stale air and the build up of unpleasant odors.
Various types of scent dispensers are employed in homes to provide pleasant fragrances. These scent dispensers include fresh cut flowers, live plants, scented candles, scent dispensers that plug into electric outlets, materials that are heated on a stove, vaporizers with added scents, and various scent blocks that are suspended so that air can circulate around them. All of these systems for adding a pleasant fragrance to the inside of a home have some major drawbacks.
Fresh cut flowers are relatively expensive even if the homeowner grows his own. It takes time to cut them, arrange them in a vase and put water in the vase. Water may need to be added more than once a day. The scent provided by the flowers is not circulated well and is essentially non-controlled. The cut flowers remain fresh for a few days or less. At the end of their useful life they have to be disposed of and the vase should be cleaned.
Live plants provide more fragrance, and can live for at least a few months. However, most of the fragrances are provided when the plants are in bloom. Many plants bloom for a short time each year. Live plants require substantial care. Water is needed frequently. Fertilizer may be required from time to time. Insect infestations may be a problem. Dead leaves have to be removed. Some plants need direct sunlight while others need indirect light. To keep plants that have different light requirements, it is necessary to move them from time to time.
Candles can provide substantial scent when burning. The fire can be extinguished from time to time to control the scent. Candles present some risks however in that they burn and can ignite other materials. Candles also discharge an oily substance into the air that will stick to most items in a home. Cleaning a room that candles have been burned in is a taxing activity.
The scent dispensers that plug into electrical outlets take an electrical outlet out of use. They use at least some electrical energy and they rely upon natural air circulation to carry scent throughout a room. Natural air circulation is not generally satisfactory in a modern energy efficient home.
Scent dispensers that are hung where air can circulate around them work reasonably well in small closed spaces. They are frequently used in automobiles for example. When such scent dispensers are used, it takes multiple dispensers to provide fragrance throughout all but the smallest rooms. These scent dispensers tend to be unattractive. There is generally no control system to control the rate at which hanging solid block scent dispensers dispense scent.
Scent materials that are heated on a stove or that are dispensed by a vaporizer use large quantities of energy. It is relatively expensive to change a liquid to a gas by adding heat. The systems add heat and moisture to a room. Heat is unacceptable in hot weather. Moisture is unacceptable when the humidity is high and can cause substantial damage to home interiors.
Safe, inexpensive, clean and controllable scent dispensers are not currently available for home use. Most known systems for dispensing scents have one or more of the drawbacks discussed above.